Wire tightener for papermaking machines



July 14, 1964 w. s. CORBIN WIRE TIGHTENER FOR PAPERMAKING MACHINES Filed April 21, 1958 2 Sheets-Sheet 1 INVENTOR.

WESLEY s. C(BRBIN BY W MM W TOE ATTORNEYS w. s. CORBIN WIRE TIGHTENER FOR PAPERMAKING MACHINES Filed April 21, 1958 July 14, 1964 2 Sheets-Sheet 2 n w w w 6 \\A/N a a G FIG-4 FIG-5 m T m V m WESLEY s. CORBIN WW y;

ATTORNEYS United States Patent M 3,140,975 WIRE TIGHTENER FOR PAPERMAKING MACHINES Wesley S. Corbin, Watertown, N.Y., assignor to The Blaek-Clawson Company, Hamiiton, Ohio, at corporation of Ohio Filed Apr. 21, 1958, Ser. No. 730,020 5 Claims. (Cl. 162-273) This invention relates to paper machinery, and more particularly to Fourdrinier paper making machines.

The invention has special relation to the control of tension in the forming wire of a Fourdrinier paper machine, and in its broadest aspects, the invention is directed to the provision of apparatus for controlling wire tension which is continuously effective and capable of such rapid response to conditions tending to cause variation from the desired tension as to maintain the tension elfectively constant and particularly to maintain proper driving of the web at all times.

The invention is especially concerned with the maintenance of the proper relationship between wire tension and engagement of the wire with the roll or rolls which drive it on the paper machine. Thus it is a common practice to provide a driven roll at the end of the machine adjacent the suction couch roll, and this driving or turning roll provides most of the power for driving the wire through the Fourdrinier section and is therefore wrapped to a substantial angular extent by the wire. There are times in the operation of the machine when the load on the wire develops surges caused by conditions such as temporary breaking of the vacuum on one or more of the suction boxes or overloading of the suction boxes, and such surges placed momentary abnormal strain in the Wire. When this occurs, the wire tends to become slack on the following side of the driving or turning roll to such extent that abnormal power is required at this roll to continue pulling the wire at the proper constant speed, and this in turn tends to cause the roll to jump or skip with respect to the wire. The result of such skipping or jumping action is then to cause ridges to form in the wire and thereby to destroy its utility.

It is a primary object of this invention to provide wire tensioning apparatus for a Fourdrinier paper machine which will protect the wire against damage from the above outlined conditions, and particularly which will assure maintenance of the wire in proper driven relation with its driving roll even during conditions of surges in the load thereon.

More specifically, it is an object of this invention to provide wire tensioning apparatus for a Fourdrinier paper machine which includes a tensioning roll mounted in close association with the wire driving roll and arranged .to respond effectively instantaneously to the development of slack in the wire on the following side of the driving roll in such manner as to maintain the wire in the desired wrapped relation with the driving roll at all times.

An additional object of the invention is to provide wire tensioning apparatus including a tensioning roll as outlined above wherein the tensioning roll is operated by a fluid pressure system arranged to maintain an effectively con- 3,140,975 Patented July 14, 1964 tively constant the angular extent of wrap of the tensioning roll by the wire.

It is also an object of the invention to provide wire tensioning apparatus as outlined above wherein the instantaneously responsive tensioning roll is operated by hydraulic power and the supplementary adjustable roll is mechanically operated.

Additional objects and advantages will be apparent from the following description, the accompanying drawings and the appended claims.

In the drawings:

FIG. 1 is a somewhat schematic and fragmentary view in side elevation of the wire section of a Fourdrinier paper machine showing the relation of the invention to the major component parts of the machine;

FIG. 2 is a hydraulic diagram;

FIG. 3 is a detail view in side elevation of the Wire tensioning roll assembly of FIG. 1;

FIG. 4 is a plan view of the assembly of FIG. 3; and

FIG. 5 is a detail side elevation of the wire stretching assembly of FIG. 1.

Referring to the drawings, which illustrate a preferred embodiment of the invention, the Fourdrinier paper machine shown somewhat diagrammatically in FIG. 1 includes the usual main components including the breast roll 19, suction couch roll 11, table rolls 12 and suction boxes 13. The forming wire W travels continuously from the breast roll to and downwardly around the couch roll, and it is driven primarily by the driving or turning roll 15, which is located just beyond and below the level of the couch roll in such position that the wire wraps a substantial angular portion thereof, shown as about The present invention is directed primarily to apparatus for maintaining the tension in the return run of the wire at a predetermined value such that the wire will in turn main tain its proper wrapped relation with the driving roll 15, and particularly that the wire will under all variations in the load thereon remain in properly driven engagement with the desired angular extent of roll 15. It should also be noted that on many paper machines, the driving roll 15 is omitted and its driving function is provided by the couch roll itself, for example as shown in Wisner et al. Patent No. 2,799,209, issued July 16, 1957, to the assignee of this application, and the description of the present invention with respect to its relation to the driving roll 15 is equally applicable to the couch roll in such installations.

In accordance with the invention, a tension roll assem bly indicated generally at 29 is mounted closely adjacent the driving roll 15, and it includes a tension roll 22 supported for generally vertical movement below the wire in closely spaced relation with roll 15 and with the uppermost portion thereof preferably above the horizontal plane of the lowermost portion of roll 15. The tension roll assembly 20 also includes means responsive to slackening of the wire between rolls 15 and 20 for effecting substantially instantaneous movement of roll 22 to a sulficient extent to maintain driving engagement of the wire with roll 15. In other Words, in the event of a surge in the load on the wire as discussed above which places such strain on the wire ahead of the couch roll as to cause slackening of the wire just beyond the driving roll 15, the tension roll 22 will be raised substantially instantaneously in order to apply such slack in the wire to temporary additional wrapping of the driving roll 15 and with a predetermined tension in order to prevent the possible jumping or skipping of roll 15 with respect to the wire and to assure properly continued driving action on the wire.

the Fourdrinier machine frame. At the back side of the machine, a lever arm 39 is secured on the end of shaft 25 and carries a counterweight 31 which is preferably of such weight as to counterbalance roll 22 to an effectively weightless condition in its optimum range of operating movements with respect to the forming wire. An additional lever arm 33 is secured on shaft 25 and is connected through a hydraulic cylinder unit 35 with one of the main cantilever beams 36 of the Fourdrinier frame, the cylinder 35 being shown as pivoted on the beam 36, and its associated piston rod 37 has a pivoted mounting 38 to the end of lever arm 35. With the roll 22 counterbalanced as shown, the cylinder 35 may be of small diameter for fast action in response to a small volume of flow, and satisfactory results have been obtained with a cylinder 35 of 2.5 inches diameter.

FIG. 2 shows a hydraulic diagram suitable for operating the cylinder 35 in accordance with the invention. The three supply lines at the right of this diagram represent respectively a pressure header 50, a tank header 51 and a drain header 52. The pressure line 55 leads through a shut-off valve 56 and a check valve 57 to a four-way valve assembly indicated generally at 60 and including a main hydraulically operated valve 61 and a solenoidoperated pilot valve 62. The valve 6%) is shown as set to supply pressure to the cylinder 35 for maintaining tension in the wire, and the pressure line 63 is accordingly connected through a reducing valve 64 with a pilot pressure operated check valve 65 from which the line 66 leads to the head end of the cylinder 35. The valve 65 is of a type which is held open for through flow only so long as the pump pressure is supplied thereto, as indicated by the supply line 67 from the pump 68, and a satisfactory valve for this purpose is a Vickers 4CT-O6l0 valve.

As already noted, FIG. 2 shows the hydraulic system set to maintain tension in the wire, with the solenoid valve 62 energized, and under these conditions the pressure in the cylinder 35 is continuously measured by the control console indicated generally at 70 and including an adjustable relief valve 71 and a pressure gauge 72. When the solenoid valve 62 is de-energized, the flow will of course be reversed, and the pressure will be supplied through line 73 and check valve 75 to the rod end of the cylinder 35. The check valve 75 is illustrated as of a type which also permits a restricted back flow therethrough when pressure is applied to the head end of the cylinder, satisfactory results having been obtained with a Vickers C2-8l5-32l valve. The remaining parts in this hydraulic diagram are shown as conventional and therefore require no further description.

When the system is set to maintain tension as shown, the applied pressure may be varied from maximum to minimum by relieving the maximum pressure applied through the valve 64 by means of the valve 71 in accordance with the reading of the applied pressure on the gauge 72. A particular advantage of this invention is that this gauge can be calibrated directly in pounds per inch of wire width to provide a direct reading of wire tension, thus eliminating the necessity for computation of the changes in tension if the pressure is read in pounds per square inch, and it is only necessary to calibrate the gauge for each specific machine in terms of the actual wire width.

In normal operation, the system Will be set as described to supply the proper pressure to the cylinder 35 to establish the desired tension in the wire in accordance with the reading on the gauge 72. Then whenever any surges in the load on the wire develop as outlined above, the slackening of the wire which takes place between the rolls 15 and 22 will be compensated for by substantially instantaneous movement of the piston rod 37 in the direction to raise the roll 22 until the proper degree of tension has been reestablished in the wire, namely when the tension in the return of the Wire again directly counterbalances the preset hydraulic pressure in the cylinder 35. This in turn increases the wrapped relation of the wire with the driving roll 15 until the momentary condition of surge has been overcome, and when this occurs, the wire tension will be momentarily greater than the hydraulic force and will therefore operate to move roll 22 downwardly until the preset condition of balance between tension and hydraulic pressure is again established.

The pressure operated check 65 provides a safety factor for preventing damage to the wire in the event of failure of the main hydraulic supply pump during operation of the machine. If the pump pressure should fail, the valve 65 would close and thus block the pressure fluid in the head end of the cylinder for a sufiicient time to allow the machine to be brought to a stop without damage to the wire.

The invention also provides for increased accuracy in the control of wire tension in conjunction with the fact that the tension as registered on the gauge 72 is in part a function of the angular degree of wrap between the wire and the tension roll 22. More specifically, if there were only line contact between the wire and roll 22, the tension change produced by a given increase in hydraulic pressure would be materially different from that at, for example, the other limit condition wherein the total Wrap is 180. Accordingly, the invention provides means for maintaining the normal operating position of roll 22 as constant as possible in order similarly to maintain effectively constant the angular degree of wrap of the wire on roll 22 under normal operating conditions.

This latter result is produced in accordance with the invention by providing adjustable means at another location spaced lengthwise of the machine from the tensioning roll assembly 20 for taking up whatever more or less permanent stretching of the wire takes place throughout its operating life. Such take-up means are indicated generally at 8! in FIG. 1 and shown in more detail in FIG. 5, as a stretcher roll 81 carried by arms 82 pivoted at 83 on the sole plates 27 and 28. The arms 82 are adjustable mechanically to raise and lower roll 81, and such adjusting means are shown as comprising a segment 85 carried by one of the bearing housings for roll 81 and driven from a suitable gear drive unit 86 shown as having a manual operating handle 88. The roll 81 is also shown as provided with a counterbalance system including counterweight 90, cable 91 and pulley 92 which will preferably counterbalance the roll to effectively weightless condition in order to minimize the load requirements on the drive unit 86.

In accordance with the invention, the roll 81 is initially preset under normal operating conditions of the paper machine in such position that the desired tension in the wire will be developed as indicated by the gauge 72. In other words, the Wire tension will hold the roll 22 in such position as to produce the desired tension reading on the gauge 72 at the desired hydraulic pressure as set by the valve 71. For increased convenience of use, this position of the roll 22 may be indicated by means such as a pointer 95 on the arm 23 and cooperating scale 96 on a marker 97 mounted on the adjacent sole plate 27, so that as often as permanent stretching of the wire occurs, with resultant raising of roll 22, the desired conditions can be reestablished by raising roll 81 until roll 22 has again been forced down to the position of coincidence between pointer 95 and index mark 96.

While the forms of apparatus herein described constitute preferred embodiments of the invention, it is to be understood that the invention is not limited to these precise forms of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

What is claimed is:

1. Apparatus for maintaining substantially constant tension in the return run of the forming wire of a Fourdrinier paper machine including a driving roll for the wire located adjacent the end of the machine, comprising a tensioning roll, counterbalancing means supporting said tensioning roll below the return run of the wire for substantially weightless generally vertical movement with respect to and in closely spaced relation with said driving roll, there being no roll between said tensioning roll and said driving roll in order to cause increased wrapping of said driving roll by the wire in response to upward movement of said tensioning roll, fluid pressure means connected to effect controlled movement of said tensioning roll with said counterbalancing means, and means for continuously supplying said fluid pressure means with pressure fluid in the direction causing upward movement of said tensioning roll and at a predetermined pressure developing correspondingly predetermined tension in the wire.

2. Apparatus for maintaining substantially constant tension in the return run of the forming wire of a Fourdrinier paper machine including a driving roll for the wire located adjacent the end of the machine, comprising a tensioning roll, counterbalancing means supporting said tensioning roll below the return run of the wire for substantially weightless generally vertical movement with respect to and in closely spaced relation with said driving roll, there being no roll between said tensioning roll and said driving roll in order to cause increased wrapping of said driving roll by the wire in response to upward movement of said tensioning roll, fluid pressure means connected to effect controlled movement of said tensioning roll with said counterbalancing means, means for supplying said fluid pressure means with pressure fluid in the direction causing upward movement of said tensioning roll, means for maintaining said pressure fluid at a predetermined pressure developing a correspondingly predetermined tension in the wire under predetermined angular conditions of wrap of said tensioning roll by the wire, and adjustable means located in spaced relation lengthwise of the machine from said tensioning roll for taking up stretching of the wire to cause said tensioning roll normally to maintain an approximately steady vertical position retaining said angular condition of wrap thereof by the wire.

3. Apparatus for maintaining substantially constant tension in the return run of the forming wire of a Fourdrinier paper machine including a driving roll for the wire located adjacent the end of the machine, comprising a tensioning roll, means including a pair of pivotal arms supporting said tensioning roll for generally vertical movement below the return of the wire and in closely spaced relation with said driving roll, there being no roll between said tensioning roll and said driving roll in order to cause increased wrapping of said driving roll by the wire in response to upward movement of said tensioning roll, means cooperating with said arms to counterbalance said tensioning roll to effectively weightless condition, fluid pressure means connected with said arms to effect controlled movement of said tensioning roll with said counterbalancing means, and means for continuously supplying said fluid pressure means with pressure fluid in the direction causing upward movement of said tensioning roll and at a predetermined pressure developing correspondingly predetermined tension in the wire.

4. Apparatus for maintaining substantially constant tension in the return run of the forming wire of a Fourdrinier paper machine including a driving roll for the wire located adjacent the end of the machine, comprising a tension roll, means including a pair of pivotal arms supporting said tension roll for generally vertical movement below the return run of the wire and in closely spaced relation with said driving roll, there being no roll between said tensioning roll and said driving roll in order to cause increased wrapping of said driving roll by the wire in response to upward movement of said tensioning roll, means cooperating with said arms to counterbalance said tensioning roll to effectively weightless condition, fluid pressure means connected with said arms to effect controlled movement of said tensioning roll with said counterbalancing means, and adjustable means located in spaced relation lengthwise of the machine from said tensioning roll for taking up stretching of the Wire to cause said tensioning roll normally to maintain an approximately steady vertical position retaining a substantially constant angular condition wrap thereof by the wire.

5. Apparatus for maintaining substantially constant tension in the :return run of the forming wire of a Fourdrinier paper machine including a driving roll for the wire located adjacent the end of the machine, comprising a tensioning roll, counterbalancing means supporting said tensioning roll below the return run of the wire for substantially weightless generally vertical movement with respect to and in closely spaced relation with said driving roll, there being no roll between said tensioning roll and said driving roll in order to cause increased Wrapping of said driving roll by the wire in response to upward movement of said tensioning roll, fluid pressure means connected to effect controlled movement of said tensioning roll with said counterbalancing means, means for supplying said fluid pressure means with pressure fluid in the direction causing upward movement of said tensioning rolls, means for maintaining said pressure fluid at a predetermined pressure developing a correspondingly predetermined tension in the wire under predetermined angular conditions of wrap of said tensioning roll by the wire, a stretch roll located in spaced relation lengthwise of the machine from said tensioning roll, adjustable mounting means for said stretch roll, and means for effecting countrolled adjustment of said stretch roll in the direction to take up stretching of the wire sufliciently to cause said tensioning roll normally to maintain an approximately steady vertical position retaining said angular condition of wrap thereof by the wire.

References Cited in the file of this patent UNITED STATES PATENTS 507,744 Marshall Oct. 31, 1893 812,899 Thacher Feb. 20, 1906 1,302,313 Coppage Apr. 29, 1919 1,816,754 White July 28, 1931 1,885,163 White Nov. 1, 1932 2,051,488 Kottlowski et al Aug. 18, 1936 2,799,209 Wisner et al July 16, 1957 FOREIGN PATENTS 25,979 France July 18, 1923 827,151 Germany Jan. 7, 1952 

2. APPARATUS FOR MAINTAINING SUBSTANTIALLY CONSTANT TENSION IN THE RETURN RUN OF THE FORMING WIRE OF A FOURDRINIER PAPER MACHINE INCLUDING A DRIVING ROLL FOR THE WIRE LOCATED ADJACENT THE END OF THE MACHINE, COMPRISING A TENSIONING ROLL, COUNTERBALANCING MEANS SUPPORTING SAID TENSIONING ROLL BELOW THE RETURN RUN OF THE WIRE FOR SUBSTANTIALLY WEIGHTLESS GENERALLY VERTICAL MOVEMENT WITH RESPECT TO AND IN CLOSELY SPACED RELATION WITH SAID DRIVING ROLL, THERE BEING NO ROLL BETWEEN SAID TENSIONING ROLL AND SAID DRIVING ROLL IN ORDER TO CAUSE INCREASED WRAPPING OF SAID DRIVING ROLL BY THE WIRE IN RESPONSE TO UPWARD MOVEMENT OF SAID TENSIONING ROLL, FLUID PRESSURE MEANS CONNECTED TO EFFECT CONTROLLED MOVEMENT OF SAID TENSIONING ROLL WITH SAID COUNTERBALANCING MEANS, MEANS FOR SUPPLYING SAID FLUID PRESSURE MEANS WITH PRESSURE FLUID IN THE DIRECTION CAUSING UPWARD MOVEMENT OF SAID TENSIONING ROLL, MEANS FOR MAINTAINING SAID PRESSURE FLUID AT A PREDETERMINED PRESSURE DEVELOPING A CORRESPONDINGLY PREDETERMINED TENSION IN THE WIRE UNDER PREDETERMINED ANGULAR CONDITIONS OF WRAP OF SAID TENSIONING ROLL BY THE WIRE, AND ADJUSTABLE MEANS LOCATED IN SPACED RELATION LENGTHWISE OF THE MACHINE FROM SAID TENSIONING ROLL FOR TAKING UP STRETCHING OF THE WIRE TO CAUSE SAID TENSIONING ROLL NORMALLY TO MAINTAIN AN APPROXIMATELY STEADY VERTICAL POSITION RETAINING SAID ANGULAR CONDITION OF WRAP THEREOF BY THE WIRE. 